Canine brain disorders are very serious as the brain controls almost every function that
occurs in the dog’s body. Brain disorders fall into three main categories:

• Inflammation or infection of the brain called encephalitis
• Cerebellar degeneration, where the cells of the dog’s brain die
• Brain tumors, which are a mass growing within the dog’s brain.

Canine distemper and rabies are the most common cause of encephalitis and dogs. Other
inflammatory brain disorders involve bacteria, foreign bodies, fungus, protozoans, and some
of the tick-borne organisms that can migrate into the brain. Infection with the canine herpes virus, either in utero or as a neonate, causes what is termed cerebellar degeneration in dogs.

A genetic predisposition for the condition is possible in a number of dog breeds. Brain
tumors affect young dogs, like the Boxer and Boston Terrier, and are usually seen in older
dogs. This is probably due to a diminished immune system which occurs as a dog ages. Secondary brain tumors result when cancer in some other part of the body metastasizes to the dog’s brain.